Finallly after a temporary ban of a few days, the things have been resolved and Fishville is back online again.
Fishville Official Page says: "Hey everyone, FishVille is now online! Your fish are happy and waiting for you to return to your tank. Thank you all again for your patience and understanding."
It also explains that, "We have been feeding your fish to keep them happy and growing during the downtime, so they should be just fine when you return to your tanks. Thank you all so much for your patience and understanding."
You can start playing the game right now at: http://apps.facebook.com/fishville/